SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b218d55f811d0acd4625fc441830794a335207101deddad6abd3b2618b18f72' 
  AND token = 'aMAEP4x1DqBsD2kFDAsNy9gpnAeYr28o+sOTVZjxYXE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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