SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51745b1dd4a4dd9a4b8a2463f01de3b30577086ee59351d0825b7ccda0c56028' 
  AND token = 'AHSQbAR27TwWpgDziX5PRbiv+5zWswaIKYM1kGW0Fvg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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