SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0e51c32208cfe2d91bf51278bee45e807d799373562fde95ddf732093f126f70' 
  AND token = 'HfbNznEtvKVsYIlSOTTs9vLbW/z25mtNZUb4dal8Gh0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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