SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4dc9fab263a78309681f778561faa2699c6346ae86615c911b506a90e9325c30' 
  AND token = 'XUD6NLdz6RgKFhWJLR7+m6FddeO7izx7FwcVYzwainU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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