SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4999a2f3d416b98bc26e4c0b9b9a2a4552d2508043eed768074f04a5cd8d7651' 
  AND token = 'RNtUnnxHA1r20Ma/TbALPLycpmg9nnAdj0mU5hjb6fc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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