SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c7e4c515712c57422bf99411280563e9abfc5af9c18bf269581ea14354651db7' 
  AND token = 'rAIRqG4ibB+0YRamJ678YSyteEhopE+IPYrPyRuKBLg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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