SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39ec3a9bac96381956228fdf165d0c5a7add2c7b098a706cf70395262b5e9afa' 
  AND token = 'n6VGajUXM82tuPxpKH/BfuJyijIR3HKivLT2qI7mb64=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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