SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5937fa0bf390736ed124421853dd1878732a164ce238e2497ba83628a58eefb7' 
  AND token = 'MXc2NOfBR4rOwt2fmPBVzO4ZKbR2LcGwfz/iZ1UJjzA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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