SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd78743b12a56c2130d6597dce0bb65b660884142540d0a635a48d34b497a4446' 
  AND token = 'LKaQGEr73SIOJUYZk2fwgTDtT3Fx1tU+WGugTx/z6lk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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