SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e056b550d4cada3be9048197e2618873dce901bcab563fc1f9a168c2096e6dc2' 
  AND token = 'i1zUnNQCzEL63EGmQlHpzTGpwTyu5iv52oTrSg0T2gY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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