SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51d1428c1c29925a5c7221d729b861cb7488f545c90f05a78e7b9c5eaf31bb17' 
  AND token = 'I3DLLdufFl++/GGYPS/hYAZ3Z9xwjC1lzV+42n0iBB4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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