SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5834f653286210430e95dbff39044ea92cbcd6bbae98d522963e34680310ebb' 
  AND token = 'zCZ7HTms/lSFPAmPhL7EPXBaLxR6QKJbA8oE1yGzBmQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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