SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e71ae39e1000b056fc9448e60f9dbb8e20c90fac300078f4409e7a13f7c17838' 
  AND token = 'dLCjACuROaIhd4ymMtQWN2EssHOlxnHh20gTOshf/2A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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