SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75bb790ca9287dd6b9086540d4bc8d1dda0de94738d4c04eb1ff873976892fca' 
  AND token = 'ryk1xpNYqkE5FjjJFEvQmQ+rp4XwLqEoYJeSa6cKsqk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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