SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f94fd7d4e760c5e966ad017ba06cc0e7483b0b5e1e00e497c4d284643fbdadb' 
  AND token = 'uyy8ZqmIFKiLu8VBk8ZLo29gyhznmOqDfX+VMghbvQA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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