SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1defdf255a452b5f7f7400d33b293dd579b4e7f6ab4dc9b9ba389ea96323686' 
  AND token = 'k+PH87DEPvamDVhJp+EMH/CDsDbKkOFZC4UJIcsN+/0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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