SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0e3cb9069a7f0e93478fdd8155431c04a0a2652201f894d7d86aab3fda945a21' 
  AND token = 'RMsv87t9AcBN3EC3nbR/CwcZWZOZ7r9tlN0V1hPO3W8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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