SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77d35d97a2a42c896f5d839a7132eb75fe5847a6798a77e630867125348562d1' 
  AND token = 'phMRcJ5SbgXx1rRG1IZBwOA26TT+Ol484LBwyfNZX9A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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