SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39bd08a7d3e8bd0883db4b80df4ccf26eed20396e8df4e1db5529c961e4703a1' 
  AND token = 'DUJlZUsSikI8TTgDOM+sTcZ/+c4/LXhsgF+1GfEuNOA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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