SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd0a3cbdd73e58e2fb50793451d66b72218dc8a26ee5deb11db80c2d051f98e39' 
  AND token = 'imholOoHGDmTFYWUX/+NziQLaL36UbkV3zSa5NeVsmc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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