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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6396d0ff3b6dfb46cd85b628c0a63ff6f538927407e3663a2f1695c2f84a1e4f' 
  AND token = 'eRf2Qcsl/RLyAmB0S3aPYbkVfzI5h0VrRWoEe4ctXH0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}