SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '49ba15674e1f3db5d04816f995f18189db302c7ab3649f9151d92cb1badc0d15' 
  AND token = 'u51mYLDFii0B6kmWhrifo8PVpQvoUQ4Jeld3j0ZftW4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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