SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1c60eba4d15b090d6b41498882166939d749ea76ddfd60a2f133adede96367b' 
  AND token = 'smSKNi0mORSyXK7IOhZC0dxkmh6eRx17iLa4fEn981M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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