SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c50fc90615bcd83fb204098796c731359dfc086274288da529068ecdceaeba8' 
  AND token = 'aiQr9aPiAvgythOtsLJRIBEf6Cfw/CZV6YvJQTeyNUg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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