SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '188043333173f811dfcf7623d8643f6cdbc31635ac0d16e97490a264142dd804' 
  AND token = 'tQXMN+Q9UqS83Z8ACG7NsTdwMSI2WyQjcTKlOwhSCig=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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