SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '340fd808f992d27242c801cd00911fca6f292a0054279478cbeedc4123d48c3c' 
  AND token = 'ZlQPuHViFwn33pSLgt1PBPp7+/gS1ld1rFzoBSCWgFQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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