SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '557c6684dd11627364f158b98e18ff712f03cf0a7d6e57e29b0668b7f2b67092' 
  AND token = 'M2T5kBwSKWqu+ujcUVM+zl6n6hmHqSAADb8ZaRcj1Ag=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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