SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7a042ff08c88db0e110a9271778961498f3ea484511a2b707d64ea312eb571a' 
  AND token = 'VXn9wdaZmN8RYGNcZhH2BZQzAW3/mSdGq9iV3EPbwQ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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