SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fcd790e75c66adc497fd7a1e3ba1e5c028022675ca70a64c4c21bc5efbb138e3' 
  AND token = 'qUdAmpDMyvVJD2WUliOcxu3an+U6AtZmDCYmK+6lzpQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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