SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4234aace3ca3bd2c6718707e6103aa8be6fb1f2a6a4712ccab9dab3302655435' 
  AND token = 'znQMo/OyFVVoyqfe+uIBJsO9u/lawEFvnkYRzUJkEqk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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