SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c505c99221d47e115dd9fb8f6bd853643f2fe435b8ea03c8e803e54ee34454f1' 
  AND token = 'd6mo7FlOX7jZl4DHljfiV4D0zL1XAV56clgbsVESmMU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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