SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '237210a58fd22baeeb1da7a6fb56ebeee858256f4ee4bf1201a375c961893564' 
  AND token = 'JgNY0XQLxrVaRgl783G/MAVQRKXDj++rOSSWgmRaoPE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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