SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '34fdd5647c9f9a1dc0d2e5d0d041fe40feb08a153ac49086464823fc96e73a1b' 
  AND token = 'Bc5eThVb9IhnNlrBsmLC+XKqnKP3MoQ5gDntlWI4m0A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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