SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92385a6f20b2fc403e1adcc5a6b8aba4a03cf2de7cbbc93916d381b306420797' 
  AND token = 'lcSMOADn0rpnwRrWJEPv7P+I4MZrKIYyFtYWp9SokJ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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