SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ff12602a11cf190cc1ecd48863e86b50e46203ca21752671c02766be9ade096' 
  AND token = 'CL8WfRvzXuSyc+1eD4118BJJJUPKHVtPjAmUIUI/KNg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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