SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6364fd54a920087b044d17c90695266c9bbe858bc3f27f04680e701b4523549a' 
  AND token = '0YeIMHn5ttkQ2Vu+ELEKQsj6zxeAuoZCIxwxpLAIqvo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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