SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd2d68c34a02469b3a4217ea9f6421e898586f8a80b435a886385d4bda1ecdf72' 
  AND token = 'J6HXKV9jHe3pgzYmbXpZdMgFRmWvTLRHDwu+Asz/O/I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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