SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c76a00e2d263dcf962fc60035d9d9326583d72d91dcf8e1147bc2d75efbe697' 
  AND token = 'mJAoNsr3yHw7Lxjzgv0N4KZwNblcZVV0OvUtiB5IMpk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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