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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b75d32d0a6e8efdf84069a13eea15e95b9faa1ec8417dfad5fcf0ad5d186a669' 
  AND token = 'g5UB4EdGXisj9lVm+EnC7etaoP8GFoixOCQrpTSF+Bo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}