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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9121df6ddd002e4db2a40bed98cf9853307c82996893cea2ceb0f40a1b60a9fa' 
  AND token = '2n6C84fNyNmrpGcwWiHrspbKXy4e3pDifwoL18rKLj4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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