SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be6254e6e42461cb2dab3398a7471197774891f05f9e5c419163dcd0e4700bb7' 
  AND token = 'U2MDsqhExMKFiQjLMWOmnnqkb64LGDH+kRwg92TN8tA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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