SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a57100ef104996942872b09368b6a0084675f812178f67220c4d4326b7c0b6ba' 
  AND token = 'C6mFPSLZ0T+siaq4BflN+AhY6v+ChoYKvnopQu4/D7M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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