SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a62361aad1cf157306968a459ed58a1d5b69c996074f136182d899da33d28406' 
  AND token = 'gmUlujVhqinYw+HtjBwh3k9lJygr1uftwe9wHkHMdNs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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