SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b213845771997c9427af67ef0fd5241db8dff9c45875bcd2e88998e7345d22e9' 
  AND token = 'vWLdRLOuBmhFoUdmCTKyOiUvhPa49CrQHg0JfaYW7gI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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