SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '77b7b33dacbe15838a6ab011f4af04b557b969e78556a1c2f257ef5a2f7f844d' 
  AND token = 'J+5OM76V1RPqcutVBJo4grhSftd0uWGI705rgA0T0oY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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