SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '939cc151a523e97d6178277369621099bb48af7558ae386bbd64c682ccdd18f3' 
  AND token = 'kcsHXxwenrHdL+GtKYqQVOKP+DOvGjG2TCoj9YSyrNw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00115

JSON explain

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