SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d48adea3ba836281384c0c12707e20881cd653c9819c1b1e80e8d752264d1e6' 
  AND token = 'zOgrUYIA5cE2BVo792ZLdHp/BHfkjumbrcViojbge9I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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