SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c972556658463992bc1fc66c6539bb328151b83e18fa964231d214ba3f7aeaf1' 
  AND token = '5qQV85FVtpMTGSKMUXsEVRG1mK+TzzosbpSlWaPZjX8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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