SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cd84953b9400943ce36115fc12d34414f18f7d65c5decbb7dd631667f84d276' 
  AND token = 'zi7G6vMIUERF9SF8uPs70yjDY1ZCvSKw+dYxDViC2sw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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