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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d37000bd5389f8b5aa4f68f28a114cc53d3e89a342d41a55598defe78688a7b' 
  AND token = 'aJVHJ8aHfTvVm5hd59Jzmz2eXQ7RYEJ5U0Ml1R2yhLs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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