SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '929be6bbe6912434b0aa7cf99fc7aa5bddff52910c80436a0322a238b01b9450' 
  AND token = 'NnniJoMdrEnmePz2WKBOViaytAYOJtZHBSaD6cYCpFk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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