SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a911a523a4e6879c44753d9b45efbe07c1770764a75945e3289b8f2bc3677a3e' 
  AND token = 'IaiOEoRoy/hGcf4AkYmqvJaj94vhG+BGqFiBo5ZVBac=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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