SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5e7aa8b5bd77c0d0299aaceb6eb6f6bcd936a63825f6c40706221add5e1d167' 
  AND token = '9bH7fzI7OXYf8TiLeliEzhN/hW073gnqTDIINmRDgUY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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