SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '455ee0ad3525a78df426add36e590750d01f993c28293e4574d423141e72951d' 
  AND token = 'RPbYzGKkHGgcoAeEFwaQMgJfZAjDA0lFZZi2CalT7Qg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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