SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31c1267a3cd41d9851e832d8c84b9296bee23e9b97a2cfab152132be8a8b2971' 
  AND token = 'bxGWAIjOoNgtRDLSMLvM9CIVZt62LnJFIU4NiNqmCL8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}