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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e2b321946d04d032aa0365f337545591e5f12c993d07342baf8b1407808322cf' 
  AND token = 'FXVmCL1468x5Do8Mng2qinFJNboN0ZYCPrsYKQuXWNI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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