SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a310ed5baaf1e3bec41c09c49890780a6da2aeb7e30d2f8ef357510b9be04f01' 
  AND token = 'tSworLBxjekXOEmlU16JqcukmE67rocmv14ZnA4cK1U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}