SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0fbd49df4020b0e196ca3db92bf8426d2db92a63f0845837b16c9879fafe4c3' 
  AND token = '8DJalaRO50LUC5/iOsGtnngBY/pKrxup3BzytITnrKQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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