SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f527aa687749e98be2fe617f91a75d3bb3d2f0f6190f1eb22aa057304891189' 
  AND token = 'Cj9fVNxNbWdMGp4N0tPjSod08PxvdTnG5h2Qhw+T3Bs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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