SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3961ccfd4883c534e08068451ac36541417cde78cd4635a7317c0cb5c18d4bd1' 
  AND token = 'y8E6KbVKL8yrXqkqEm6bIoPTUzmGJZ5c48tB/nGTdws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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