SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b565477d55686f84fb1758f11dc4c25b12e7f36ae54113d84341c2861025b8b3' 
  AND token = 'B6rcLxQi/XC8kaE2Zzvt7XzyPrIhCS6jDYzPdT22Ak0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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