SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '756be0abf242084ac0b08681c4031d49dadf852786d677baec17647a6f58408b' 
  AND token = '5RgIJOHb1OaNUSJe/JF13XgW4Gr+kaq+RhHxXTONMRI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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