SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a8add5754c4e5838db6c3bd753931a2e9efbd1adb0c18343fa1ac52032712a8' 
  AND token = 'Mek0uypY0YFiLxFqcBeTTKAD6Hkndz3bQV4NxcMCEmg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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